Transferring Existing Forum to vB 4.0 Question

I'm relatively new to owning / being the admin of a forum, so I don't really know the answer to this question:

When vB 4.0 comes out, will all the "modifications" and tweaks that I've done to my forum work for the most part? or... is it going to be building from the ground up again?

 

I believe, for the most part, rebuild or wait for others to rebuild.

One of the best posts on the topic is #33 here:
http://www.adminaddict.net/forum/vbulletin/upgrading-vb4-958/index2/#post17382

 

Thanks!